Conventionally, as a linear mobile motor that is adapted such that a field pole as a stator to be used for carrying of a machine tool or a semiconductor manufacturing apparatus, and an armature as a mover move relative to each other, there is a motor as shown in FIG. 9. FIG. 9 is a front sectional view of a conventional linear mobile motor. Here, an example of a moving-coil-type linear mobile motor that uses an armature as a mover will be described. Reference numeral 252 denotes a stator, reference numeral 255 denotes a mover, reference numeral 250 denotes a plate field yoke, and reference numeral 251 denotes a plurality of permanent magnets with different magnetic poles arranged alternately along the filed yoke 250 (vertical to the paper). A field pole composed of the field yoke 250 and the permanent magnets 251 constitutes the stator 252. Reference numeral 255 denotes a mover having a frame 254 provided with a number of coils 253 that are provided opposite to the permanent magnets 251 via a magnetic gap. The coils 253 are anchored with resin molding (not shown), and the frame 254 and the coils 253 constitute the armature. Further, the frame 254 can be a frame for fixing a transporting member for carrying a load or may be a transporting member itself. Pipes 260 and 256 are arranged at the bottom and sides of the field yoke 250. The pipes 260 and 256 are connected to an air blower (not shown) such that air flows through the pipe. A vent hole 257 for allowing a gap between the mover 255 and the stator 252 and the pipe 260 to communicate with each other is empty in the field yoke 250 such that the air flow through the pipes flows into the gap. Vent holes 258 for allowing a gap between the mover 255 and the stator 252 and the pipes 256 to communicate with each other are empty in the field yoke 250 and the permanent magnets 251 such that an air flowing through the pipes flows into the gap. By adopting such a configuration, in the linear mobile motor, a method of radiating the heat of a mover when a driving current continues to be supplied to the coils 253 from a power source in order to raise the thrust of the motor, and consequently temperature rises and calorific power increases due to an increase in the internal resistance of the coils 253 is disclosed (JP-A-2000-341911).
Meanwhile, in the aforementioned related art, the heat from the coils is radiated only by air blowing. Thus, when the motor is continuously driven long time, or when a high load is applied to the motor, heat cannot be radiated sufficiently, and consequently temperature rises and calorific power increase due to an increase in the internal resistance of the coils. Then, the heat is transferred via the frame to the transporting member fixed to the frame or to an upper part of the frame. As a result, the problem that thermal distortion of the frame and the transporting member is caused was not solved. In particular, in the portions of the frame facing the permanent magnets, the temperature of the coils rises with the lapse of time. Accordingly, the deflection caused by the thermal distortion that occurs in the longitudinal direction increases. Further, if the heat radiated from the coils of the linear or curved mobile motor increases, the distortion of the frame in the direction facing a row of the permanent magnets also increases, and consequently, the magnetic gap between the coils and the magnets fluctuates. As a result, since this deteriorates the traveling performance of the linear mobile motor, thereby causing an error in the degree of positioning accuracy, it was difficult to realize high-accuracy positioning. Further, since the magnetic gap fluctuates, it was also difficult to provide a motor that can make a curved movement having the fluctuation of the gap even if there is no thermal distortion.
The present invention has been made to solve the aforementioned problems. It is therefore an object of the invention to provide a radiator for a linear or curved mobile motor capable of removing the thermal distortion of a mover or a transporting member, and a high-accuracy, hi-reliability linear or curved mobile motor using the radiator.